Mobile electronic devices such as smart phones, portable navigation devices (mobile device/PNDs) and integrated navigation systems that include GNSS (Global Navigation Satellite Systems) signal reception and processing functionality are well known and are widely employed as in-car or other vehicle navigation systems. In general terms, a known electronic device having navigation functionality comprises a processor, memory (at least one of volatile and non-volatile, and commonly both), and digital map data stored within said memory. The processor and memory cooperate to provide an execution environment in which a software operating system may be established, and additionally it is commonplace for one or more additional software programs to be provided to enable the functionality of the mobile device/PND to be controlled, and to provide various other functions.
Such devices also include a GNSS antenna, such as a GPS antenna, by means of which satellite-broadcast signals, including location data, can be received and subsequently processed to determine a current location of the device relevant to the digital map. The device may also include electronic gyroscopes and accelerometers which produce signals that can be processed to determine the current angular and linear acceleration. The determined acceleration may then be used in conjunction with location information derived from the GPS signal to determine the velocity and relative displacement of the device and thus vehicle in which it is typically mounted. Such sensors are most commonly provided in in-vehicle navigation systems, but may also be provided in the mobile device/PND itself.
In recent years, such devices have also been used in systems to alert drivers when they are approaching known locations of known hazards, such as that of speed enforcement devices (i.e. speed traps and enforcement cameras) and certain other hazards including road hazards, such as school zones, accident black spots, road works, and weather hazards such as black ice, snow, flooding and heavy rain, brush fires etc. Speed cameras are provided to slow traffic often at locations known to represent accident black spots, and may themselves represent hazards as other road users may brake suddenly and unexpectedly, which is a common response by some drivers when they see a speed enforcement device. Devices that warn a driver of the presence of a speed enforcement device improve the driver's safety since they warn the driver of the location of such hazards.
In such systems, a device having a GPS antenna and access to a database containing the location of hazards including speed traps, accident black spots, etc is typically provided in a vehicle. The device is configured to warn a driver when the vehicle, using the location information derived from the GPS signal, is approaching the location of a hazard stored in the database. One such system is described, for example, in WO 01/55744 A2. The locations of the hazards may be stored locally in a data repository of the mobile device/PND, but may be periodically updated at the mobile device/PND by, for example, the mobile device/PND receiving an update by wireless communication from a central server.
As will be appreciated by those skilled in the art, one of the important aspects of such systems is the accuracy and freshness of the information in the database. For example, it is undesirable to provide a warning to a user of a hazard such as a speed camera that is no longer present on the stretch of road, or to incorrectly indicate the speed limit on a stretch road associated with a speed camera in the database. In an effort to improve accuracy and freshness of such data, it is known to collect and utilise reports from drivers and other users indicating the presence or absence of speed cameras, and to provide this updated information to other members of the community in a real-time manner.
An example of one such system is the Trapster® application for mobile devices, and which is described in detail at www.trapster.com. In this application, all users of the app are asked to report or validate the status of speed traps, enforcement cameras and the like. As result of these reports, a digital map can be shown to a user with various icons and colours representing different trap types, and in some cases their associated confidence levels. For example: a green trap icon is displayed to indicate the presence of an unverified trap; a yellow trap icon is displayed to indicate that a trap has been verified by another user; a red trap icon is displayed to indicate that a trap has been verified by multiple users, and thus has the highest confidence level associated with it. The application also allows users to report other hazards, such as: police traps, e.g. an active sighting of a police speed trap, or a police vehicle currently observing traffic; construction zones, e.g. road works; brush fires; road closures; children at play; icy roads; etc. These hazards are shown to other users, again by means of an icon indicating a location on the digital map of the hazard stored in the database.